-34- 
84° F. Here they regained their nobility in about 5 minutes and the 
poison took effect. Counts' of deed and dying flies rere made et 
the end of 46 to 48 hours. Under these conditions an acetone- solution 
of rotenone (1:5,000) killed p'bout 40 nercent of the flies. Then 
active caged flies ■T-re treated in the same way at room temperature, 
the 1:5,000 solution killed about 90 percent. 
Tests in the cold room led to one significant result th r t could 
not have been obtained at higher temperature, With immobile flies 
it was shown that the effect of the 1;5,000 treatment depends on the 
position and exposure of the insect's body <~ith resnect to the set- 
tling fog. When the flies were placed en their feet so that the fog 
settled on the wings and dorsum, they -ere not affected. Wnen they 
were placed on their backs so that the fog fell on the venter and 
pleural area many ^ere killed. Then they ^ere olaced on their backs 
and the heads or abd. omens were covered the mortality was greatly re- 
duced, indicating that the poison orobably enters ell three regions 
of the body when the flies on their bpeks ere fully exoosed. Although 
the treatments in the cold were of the greetest possible uniformity, 
the results from dey to day varied as. much as those obtained at higher 
temperatures. Later tests were therefore made at 83° to 84° F. with 
the apparatus described above. For each test 50 chilled flies 2 days 
old ^ere counted out into a large petri dish, ^hich ^as tnen covered 
"'ith wire screen. When the flies had resumed their normal activity, 
the dish was placed in the bottom of the copper tray and the spraying 
chamber was assembled above it. Absolute ethyl alcohol -as ised as 
the solvent for rotenone and relpted compounds because it has no. 
permanent, effect on the flies. Alcohol was ^referred to acetone for 
"ork at high temperatures because it does not evaporate so rapidly. 
At 20 pourids' pressure about 10 cc. of the alcohol solution '-•as 
sprayed into the chamber ••ith the flies exposed. The spraying operation 
took about 10 seconds, after Hr.ich the flies ^ r ere exposed to the set- 
tling fog for 3 minutes, and -ere- then transferred to e cei-e "ith food. 
Final counts of dead and moribund, flies were made at- the end of 46 to 
48 hours. Results are expressed as percentage of effect, each dead 
fly equalling 2 nercent and each moribund fly 1 percent. The rearing, 
snreying, ^nd observation of treated flies were all done in the same 
constant-temperature room. The following average results were obtained 
in terms of percentage of effect of 1:5,000 solutions: Rotenone 85.4 
percent (10 tests), dihydrorotenone 65.5 oercent (10 tests), rotenone 
hydrochloride 30 percent (10 tests), acetyl rotenone 25 percent (7 
tests). The following compounds produced less than a 10-oercent effect, 
hence cannot be classified in order of vrlue until tested at higher 
concentrations: Isorotenone, des 'xyrottn ore, dehydrorotenone, rotene-.ic 
aeid, dihydrorotenonic acid, acetyl rotenolone,* end acetyl dinydro- 
rotenolone. 
Gnedinger and Corl (_11_8) in 1932 reported on the relative toxicity 
of pyrethrins end rotenone es fly-sprpy ingredients. Mixed ^;,-rrthrins 
(66.8 percent pyrethrin I and 33.2 nrrcent pyrethrin II) in a highly 
refined Pennsylvania mintral oil, "Deocene" (£3.4 --. r 100 cc), 
caused pn rvera^e knock-dO'"n of 94 nercent and en averr.Te kill of 46 
